The present invention concerns electronic watches and more precisely those in which correction of the time display is effected by means of a manual rotary control member such as a time setting stem. It applies more particularly to analog display watches in which the display members, for example hands, are driven by a stepping motor, because it is in this case that the invention provides the most advantages, although it can also be useful in digital or pseudo-analog display watches.
In electronic watches comprising at least an hours hand and a minutes hand, which are driven by a stepping motor, the time display is generally corrected mechanically by means of a time setting stem having two axial positions. Very often, in the same way as in conventional mechanical watches, rotating the stem in one direction or the other, in the position in which it is pulled out, makes it possible to correct minutes and hours at the same time, with the pushed-in position of the stem being a rest position in which rotary movement of the stem does not have any effect.
Some watches of this type are so designed that it is also possible to change rapidly the hour hand setting, as in the case when the user is travelling between time zones. One construction involves selecting the information to be corrected, hours and minutes or only hours, by rotating the stem in one direction or the other, while keeping it in its pushed-in position, pulling the stem out, and then turning it again to correct the selected information, the rotary movement of the stem in one direction or the other then making it possible to turn the watch forwards or backwards.
Such correction systems require relatively complicated mechanisms which in most cases involve a high degree of precision and are therefore expensive. In addition, such mechanisms are bulky.
Moreover, as the electronic correction of time information by means of pushbuttons in digital display watches suffered from disadvantages, in particular the disadvantage of requiring complicated operating movements which do not intuitively spring to mind, the attempt was made to replace such control members by a time setting stem to which the users of watches were more accustomed. Various designs using a rotary control stem have been proposed. One such design comprises, as in the case of electromechanical watches, using a control stem which has two axial positions, and rotating the stem in one direction or the other, in the position in which it is pulled out, in order simultaneously to correct minutes and hours in two directions, the speed of correction depending on the speed of rotation of the stem. This design suffers from disadvantages. In actual fact, either the time setting operation is carried out at a rate which makes it possible to watch the minutes display, in which case correction in respect of hours is slow, or else the time setting operation is carried out at a rapid rate, although in that case it is difficult to watch the minutes units in order to stop the correction operation at the desired moment. Moreover, there is the danger of losing the time, when correction in respect of time zone is effected.
Other known digital watches comprise a winder crown which, when it is pulled out, permits correction in respect of hours or minutes, in response to a rotary movement of the crown in one direction or the other. This method suffers from the same disadvantages as the design described above, for different reasons. The correction operation is a slow one since it can be carried out only in one direction. The danger of losing the time is because it is difficult for the user of the watch to know in what direction the crown is in fact rotated, particularly when beginning the operation.
It is also known for the hours display and the minutes display to be altered by rotating the time setting stem at a slow speed or at a high speed respectively, the display moving forwards or backwards depending on the direction of rotation. Such a design does not eliminate the danger of losing the time.